The Solidification Organization Research Of Mg-Gd Alloy Under The Action Of The Alternating Magnetic Field

With the rapid development and high requirements of erospace, automobile,electronic science and technology, magnesium alloy has been widely used.In order to makebetter application in various fields, magnesium alloy needs further to improve themechanical properties and materials processing performance with tissue homogenizationand grain refinement, this applicati-on of magnesium alloy in the field of modern scienceand technology development has the profound significance.In this paper, using the semi-solid electromagnetic stirring equipment to prepare theMg-Gd alloy castings with the different content of Gd, such as5.5%,10%and15%, andits diameter is90mm, high is160mm, in the solidification process of magnesium alloymelting liquid, to applying electromagnetic stirring force with the voltage less than200Vand the frequency less than20Hz. Using metallographic microscope, scanning electronmicroscopy, X-ray diffraction and mechanical performance test to tset magnesium alloyascast structure morphology, grain size and hardness, and research content of rare earthelement Gd, electromagnetic stirring process on the microstructure and hardness ofmagnesium alloy are studied.It was found that in magnesium alloys melting process, the adding of Gd can makethe grain refinement of magnesium alloy, and with the increase of Gd content, grain sizewill be reduced, with the Gd content increased from5.5%to10%and15%, the grain sizerises from340μm to282μm and268μm, the hardness rises from28HRB rise to42HRBand48HRB.Preparation of magnesium alloy electromagnetic stirring processcan make theorganization of the alloy grain refine, reduce the solute segregation in Gd in the matrix, areduction in the number of inclusions and the morphology difference of each part of theingot casting, at the same time, it also can improve the degree of supersaturation of thesecond phase Mg5Gd, improve the hardness of magnesium alloy. The voltage is less than200V, less than20Hz frequency range, raise the voltage and frequency values can get better effect of electromagnetic stirring, such as the frequency is8Hz, the voltageis from80V to120V, to prepare the Mg-Gd alloy with the Gd content is11%, the hardness is62HRB and74HRB; When the cooling rate increased by5.5℃/min to12℃/min, thefinal semisolid organization of he magnesium alloy with10%Gd content will increase inthe number of defects such as shrinkage cavity and inclusions.